I've been to Cornwall loads of times as a mate moved there about 20 years ago, so have gone down to see him a number of times. I've always thought it was over-rated and the weather has largely been pants when I've been there and nearly always rains - yes, the winters aren't as bitter as in the East, but the summer days are nearly always 5-10 degrees colder than in the south east with more rainy and windy days. Some nice places to see, but becoming more and more crowded.
I am biased as lived here for a number of years, but don't think you can beat east and south east Kent and the bordering East Sussex. I say that from a biased point of view, but we have a Shepherds Hut/holiday let too and the feedback we always get beyond the Hut itself is that the area is a hidden gem - set in a rural location with loads of walks where you see no one other than sheep, cows and tractors and country pubs, short trips to a load of cracking beaches and coastal and tourist towns - Hythe, Canterbury, Rye, Tenterden etc and lots of activities for kids activities on the doorstep - Port Lympne, RHDR, Dover Castle etc. Plus, although this year has been an exeption, the weather is usually pretty good in the summer months and certainly better than the West and North.
I'm off to York in a couple of weeks and haven't been before, so am looking to that as my main summer getaway and seeing the City and Noth Yorks. I hear good things, but not sure I could live there as generally can't stand big-headed loud-mouthed Yorkshiremen, who don't seem to be able to got two sentences without mentioning Yorkshire, but that may well be accentuated and worsen when they travel south, so I'm hoping not to hear so much of their fullofitness when I visit them on their own doorstep!